1. Field of the Invention
The present invention relates to a process for the preparation of inducers of non-specific immunity from viruses by a two-stage treatment which results in inactivation of the virus with, at the same time, lowering of the antigenicity but without destroying the non-specific immunizing activities.
2. Description of Related Art
According to A. Mayr, non-specific immunization means the acquisition of a rapidly developing protection, which is maintained for varying periods and is not pathogen- and not antigen-specific (paraspecific), of an individual against a plurality of quite different infections, toxins and antigens. The paraspecific protection (non-specific immunity) develops due to the stimulation of the paraspecific part of the cellular and humoral immune system.
Non-specific immunity may be acquired in a natural way during the course of an infection, or by treatment with inducers of non-specific immunity, immunomodulators, biological response modifiers (BRM) etc. Examples of known inducers of non-specific immunity are inactivated fowl pox, parapox or orthopox viruses [Tierarztl. Praxis 14, pages 237-244 (1986)].
Known inducers of non-specific immunity are inactivated by gamma rays, by heating or by chemical processes (DE-OS (German Published Specification) 2,714,665). A two-stage inactivation process has not until now been disclosed for the preparation of inducers of non-specific immunity.
The methods used are not new as techniques per se. However, they have been used in virology to date exclusively for other purposes. Zwartouw et. al. [J. gen. Microbiol. 38, 39-45 (1965)] made use of heat and alkalization to isolate precipitating antigens from vaccinia particles. These operations were not aimed at inactivation, they had the object of detecting antigens following different pretreatments of the starting material with serum, which contained antibodies against the complete virus, in the supernatant of the treated virus suspensions.
In the chosen system, these authors were able to demonstrate only that the antigen-antibody reaction taking place after the chemically thermal treatment of the vaccinia virus was quantitatively less distinct.
Experience to date with inducers of non-specific immunity from poxviruses and paramyxoviruses has shown that 2 criteria are important for the activity of inducers of this type:
1. inactivation under mild conditions and
2. a reduction in the total antigenicity with, at the same time, retention of the non-specific immunizing activities.